Background: Lumbar puncture is an essential procedure in the emergency department for the evaluation of meningitis. Subcutaneous injection of lidocaine prior to lumbar puncture for local anesthesia is not a pain free procedure. The J-Tip Device allows an intradermal needle-free jet injection of 1% buffered lidocaine. This study compares needle-free jet injection of lidocaine to saline in reducing pain prior to lumbar puncture in infants.